Court.java

@Entity
public class Court {

	@EmbeddedId
	private CourtId id;
	
	private String name;
	
	@OneToMany(mappedBy = "playedOn")
	private Set<Game> games = new HashSet<Game>();

	...
}

Game.java

@Entity
public class Game {

	@EmbeddedId
	private GameId id;
	
	private String name;
	
	@ManyToOne
	private Court playedOn;

	...
}

mongodb_mapping.json

> db.Game.find()
{
	"_id" : {
		"category" : "primary",
		"sequenceNo" : "456"
	},
	"name" : "Bruce - Dwain",
	"playedOn_id" : {
		"countryCode" : "DE",
		"sequenceNo" : "123"
	}
}
> db.Court.find()
{
	"_id" : {
		"countryCode" : "DE",
		"sequenceNo" : "123"
	},
	"games" : [
		{
			"id.sequenceNo" : "456",
			"id.category" : "primary"
		}
	],
	"name" : "Center Court"
}

orm_ddl.sql

create table Court (
  countryCode varchar(255) not null, 
  sequenceNo varchar(255) not null, 
  name varchar(255),
  primary key (countryCode, sequenceNo)
) ENGINE=InnoDB

create table Game (
  category varchar(255) not null, 
  sequenceNo varchar(255) not null, 
  name varchar(255), 
  playedOn_countryCode varchar(255), 
  playedOn_sequenceNo varchar(255),
  primary key (category, sequenceNo)
) ENGINE=InnoDB